This application is based on Application No. 2001-13071, filed in Japan on Jan. 22, 2001, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an automotive electric power supply assembly and particularly to an automotive electric power supply assembly capable of supplying electricity to electrical loads requiring a plurality of different voltages.
2. Description of the Related Art
Generally, an automotive vehicle is provided with an electric power supply assembly having an automotive alternator which is driven by an engine, charges a battery, and supplies electricity directly to an electrical load, etc. Conventionally, the electric power supply assembly has one voltage.
However, in recent years, rapid-defrosting electric heaters for windows and rapid heaters for automotive vehicle interiors have been installed for vehicle comfort, and catalyst heaters have been installed as exhaust-gas cleaning measures. As a result, because electrical loads have increased, the amount of electrical power consumed has increased, and conditions can no longer be handled by conventional electric power supply assemblies having one voltage, raising demand for electric power supply assemblies having a plurality of voltages.
In answer to demands for such electric power supply assemblies, automotive electric power supply assemblies capable of outputting two voltages have been proposed, for example, in Japanese Patent Laid-Open No. HEI 7-39199.
FIG. 11 is a circuit diagram of a first conventional automotive electric power supply assembly such as that disclosed in Japanese Patent Laid-Open No. HEI 7-39199, for example.
In FIG. 11, an automotive alternator 1 includes: a Y-connected three-phase alternating-current winding 2; a first rectifier 3 connected to the three-phase alternating-current winding 2 for full-wave rectification of an alternating-current output therefrom; a second rectifier 4 connected in parallel to the first rectifier 3 for full-wave rectification of the alternating-current output from the three-phase alternating-current winding 2; a field winding 7 for applying a magnetic field to the three-phase alternating-current winding 2; and a voltage regulator 8 for adjusting voltages output from the first and second rectifiers 3 and 4 by switching a magnetizing current for the field winding 7.
A first output terminal 5 of the first rectifier 3 is connected to a positive electrode of a low-voltage battery 10 through a changeover switch 14, and a negative electrode of the low-voltage battery 10 is grounded. A low-voltage electrical load 11 is connected in parallel to the low-voltage battery 10. A second output terminal 6 of the second rectifier 4 is connected to a positive electrode of a high-voltage battery 12, and a negative electrode of the high-voltage battery 12 is connected to the positive electrode of the low-voltage battery 10. A high-voltage electrical load 13 is connected in parallel to the series circuit of the low-voltage and high-voltage batteries 10 and 12.
The voltage regulator 8 includes: a first terminal 8a connected to a first end of the field winding 7; a second terminal 8b connected to an ignition switch 16 for activating the voltage regulator 8 together with the automotive vehicle by being closed when the vehicle is started; a third terminal 8c connected to a second end of the field winding 7 and connected to the first output terminal 5 through the changeover switch 14; a fourth terminal 8d connected to the second output terminal 6; and a fifth terminal 8e connected to a common terminal E.
The voltage regulator 8 is constituted by components 81 to 91. More specifically, a collector of a power transistor 81 is connected to the first terminal 8a, an emitter of the power transistor 81 is connected to the fifth terminal 8e, and a base of the power transistor 81 is connected to the second terminal 8b through a base resistor 82, the power transistor 81 switching a field current. A collector of a control transistor 83 is connected to the base of the power transistor 81, and an emitter of the control transistor 83 is connected to the fifth terminal 8e, the control transistor 83 controlling an on-off state of the power transistor 81. An anode of a Zener diode 84 is connected to a base of the control transistor 83, the Zener diode 84 activating the control transistor 83 by conducting at or above a predetermined voltage. First and second voltage-dividing resistors 85 and 86 are connected in series between the third terminal 8c and the fifth terminal 8e, the first and second voltage-dividing resistors 85 and 86 dividing and detecting a voltage from the low-voltage battery 10. Third and fourth voltage-dividing resistors 87 and 88 are connected in series between the fourth terminal 8d and the fifth terminal 8e, the third and fourth voltage-dividing resistors 87 and 88 dividing and detecting voltages from the low-voltage and high-voltage batteries 10 and 12. Moreover, the first and second voltage-dividing resistors 85 and 86 are preset such that a voltage at the third terminal 8c (the first output terminal 5) becomes a first adjusting value, and the third and fourth voltage-dividing resistors 87 and 88 are preset such that a voltage at the fourth terminal 8d (the second output terminal 6) becomes a second adjusting value that is higher than the first adjusting value. Furthermore, a first reverse-current protection diode 89 is connected between a voltage division point between the first and second voltage-dividing resistors 85 and 86 and a cathode of the Zener diode 84, a second reverse-current protection diode 90 is connected between a voltage division point between the third and fourth voltage-dividing resistors 87 and 88 and the cathode of the Zener diode 84, and a suppression diode 91 is connected between the first terminal 8a and the third terminal 8c, in other words, in parallel to the field winding 7.
Next, the operation of the first conventional automotive electric power supply assembly constructed in this manner will be explained.
First, when the ignition switch 16 is closed to start the vehicle with the changeover switch 14 closed and the first output terminal 5 and the low-voltage battery 10 connected, a base current flows from the low-voltage battery 10 through the base resistor 82 to the power transistor 81, turning the power transistor 81 on. Thus, an electric current flows from the low-voltage battery 10 through the field winding 7 and the power transistor 81. Then, a rotor (not shown) of the automotive alternator 1 is driven by the engine of the vehicle, and a low voltage suitable for charging the low-voltage battery 10 is output from the first output terminal 5. At this time, the generated electric potential at the second output terminal 6 is the same as at the first output terminal 5, but because a high electric potential from the high-voltage battery 12 is applied to the second output terminal 6, the output current is zero and electric power is not output from the second output terminal 6.
Now, the voltage regulator 8 compares a detected voltage from the first and second voltage-dividing resistors 85 and 86 (the voltage at the third terminal 8c) and the first adjusting value by means of the Zener diode 84. When the detected voltage is higher than the first adjusting value, that is, when the voltage at the voltage division point between the first and second voltage-dividing resistors 85 and 86 is higher than the Zener voltage of the Zener diode 84, the magnetizing current supplied to the field winding 7 is reduced by turning the Zener diode 84 on, turning the control transistor 83 on, and turning the power transistor 81 off. When the detected voltage is lower than the first adjusting value, the magnetizing current supplied to the field winding 7 is increased by turning the Zener diode 84 off, turning the control transistor 83 off, and turning the power transistor 81 on. Thus, the voltage at the third terminal 8c is adjusted to be constantly at the first adjusting value.
The third and fourth voltage-dividing resistors 87 and 88 are preset to the second adjusting value and a similar operation to the constant voltage control of the first adjusting value described above is performed by a logical OR operation, but when the changeover switch 14 is closed, the voltage regulator 8 operates on the basis of the first adjusting value without activating the Zener diode 84 because a terminal voltage of the high-voltage battery 12 is lower than the second adjusting value.
When the changeover switch 14 is opened, the output electric current from the first output terminal 5 is cut off and only the voltage of the low-voltage battery 10, which is lower than the first adjusting value, is applied to the third terminal 8c of the voltage regulator 8. As a result, because the Zener diode 84 is turned off, the control transistor 83 is also turned off, and the power transistor 81 is turned on, the output voltage of the automotive alternator 1 rises. Consequently, the automotive alternator 1 outputs from the second output terminal 6 a high voltage suitable for charging the high-voltage battery 12, that is, a voltage determined by the second adjusting value on the basis of the detected voltage from the third and fourth voltage-dividing resistors 87 and 88 of the voltage regulator 8.
Thus, according to this first conventional automotive electric power supply assembly, it is claimed that one of two different voltages can be stably output irrespective of the operating conditions of the engine by switching over a changeover switch 14.
Automotive electric power supply assemblies designed such that required output can be extracted from regions where rotational frequency is low through regions where rotational frequency is high have also been proposed conventionally, such as in Japanese Patent Laid-Open No. HEI 4-208100, for example.
FIG. 12 is a circuit diagram of a second conventional automotive electric power supply assembly such as disclosed in Japanese Patent Laid-Open No. HEI 4-208100, for example.
In FIG. 12, an automotive alternator 1A includes: a three-phase alternating-current winding 2A; and a field winding 7 for applying a magnetic field to the three-phase alternating-current winding 2A. The three-phase alternating-current winding 2A is constituted by Y-connected main winding portions 2-1, and auxiliary winding portions 2-2 connected in series to the main winding portions 2-1. In addition to the automotive alternator 1A, this second conventional automotive electric power supply assembly includes: a first rectifier 3 connected to the main winding portions 2-1 for full-wave rectification of an alternating current output therefrom; a second rectifier 4 connected in parallel to the first rectifier 3 for full-wave rectification of the alternating current output from the main winding portions 2-1; a third rectifier 17 connected to the auxiliary winding portions 2-2 for full-wave rectification of an alternating current output therefrom; and a voltage regulator 8A for adjusting voltages output from the first, second, and third rectifiers 3, 4, and 17 by switching a magnetizing current supplied to the field winding 7. Output from the third rectifier 17 is supplied through first and second switches SW4 and SW4xe2x80x2 to an electrical load and a battery 18. A controller 19 is activated by a rotational frequency detection signal from the automotive alternator 1A, and operates the first and second switches SW4 and SW4xe2x80x2 so as to turn the first and second switches SW4 and SW4xe2x80x2 on below a predetermined rotational frequency and turn the first and second switches SW4 and SW4xe2x80x2 off at or above the predetermined rotational frequency.
Next, the operation of the second conventional automotive electric power supply assembly constructed in this manner will be explained.
First, when the first switch SW4 is closed, an electric current flows from the battery 18 to the field winding 7, initiating excitation. In this state, a voltage is generated in the main winding portions 2-1 when a rotor (not shown) of the automotive alternator 1A is rotated. A voltage rectified by the second rectifier 4 charges the battery 18 and is supplied to the electrical load. A voltage rectified by the first rectifier 3 is applied to the field winding 7. In a steady state, the field winding 7 is excited by the voltage from the first rectifier 3.
The voltage supplied to the electrical load is kept at a predetermined value by the voltage regulator 8A in the following manner: the voltage supplied to the electrical load, which is divided by first and second voltage-dividing resistors 85 and 86, is compared to a voltage at a Zener diode 84, and if the former is greater than the latter, a control transistor 83 is turned on, and a power transistor 81 is turned off, reducing the magnetizing current supplied to the field winding 7, and if the voltage supplied to the electrical load is less than the voltage at the Zener diode 84, the control transistor 83 is turned off, and the power transistor 81 is turned on, increasing the magnetizing current supplied to the field winding 7. Thus, the voltage supplied to the electrical load is adjusted to be constant.
Now, the main winding portions 2-1, which have a small number of winds, produce almost no output when the rotational frequency is low, and do not have the capacity to recharge the battery 18 through the second rectifier 4 on their own. However, when the auxiliary winding portions 2-2 are added to the main winding portions 2-1, the battery 18 can be recharged, albeit by a low output, even if the rotational frequency is low, because the number of winds is increased.
Because the controller 19 turns the first and second switches SW4 and SW4xe2x80x2 on if the rotational frequency is lower than the predetermined value, the output from the auxiliary winding portions 2-2 added to the main winding portions 2-1, in other words, the voltage rectified by the third rectifier 17 is supplied to the battery 18, recharging the battery 18.
If the rotational frequency rises, the output from the main winding portions 2-1 starts up, and the battery 18 is charged by the voltage from the second rectifier 4. When the rotational frequency becomes greater than the predetermined value, the controller 19 turns the first and second switches SW4 and SW4xe2x80x2 off, and the supply of the voltage from the third rectifier 17 to the battery 18 is terminated. Thereafter, the battery is charged by the voltage from the second rectifier 4 alone.
Thus, according to this second conventional automotive electric power supply assembly, because the voltage from the third rectifier 17 is output during low-speed rotation and the voltage from the second rectifier 4 is output during high-speed rotation, it is claimed that the battery can be charged even during low-speed operation and high output can be achieved during high-speed operation.
In the first conventional automotive electric power supply assembly, because either of two different voltages can be output by switching over a changeover switch 14 in the above manner, one problem has been that the two different voltages cannot be supplied simultaneously to the low-voltage electrical load and the high-voltage electrical load.
Similarly, in the second conventional automotive electric power supply assembly, because the voltage from the third rectifier 17 is output during low-speed rotation and the voltage from the second rectifier 4 is output during high-speed rotation by turning the switches SW4 and SW4xe2x80x2 on and off in response to the rotational frequency, one problem therewith has also been that the two different voltages cannot be supplied simultaneously to the low-voltage electrical load and the high-voltage electrical load.
The present invention aims to solve the above problems and an object of the present invention is to provide an automotive electric power supply assembly enabling at least two different voltages to be output simultaneously.
In order to achieve the above object, according to one aspect of the present invention, there is provided an automotive electric power supply assembly including:
a rotor provided with a field winding, the rotor forming a rotating magnetic field when a magnetizing electric current is supplied to the field winding;
a stator provided with at least one three-phase alternating-current winding constructed by forming three winding phase portions into a Y-connection, the stator being disposed so as to envelop the rotor and to generate an output when the rotating magnetic field is applied thereto; and
a voltage regulating means for adjusting the output from the stator by controlling the magnetizing electric current supplied to the field winding,
wherein each of the winding phase portions constituting the three-phase alternating-current winding is divided into a plurality of winding divisions, and
outputs from the winding divisions are simultaneously extracted independently and supplied to different electrical loads.
The outputs from the winding divisions may each be subjected to full-wave rectification by an independent rectifier.
Each of the winding phase portions may be divided into first and second winding divisions.
The outputs from the first winding divisions may be adjusted so as to be constant by the voltage regulating means, the outputs from the second winding divisions being controlled so as to be constant by a voltage division ratio based on the number of turns in the winding divisions.
The first winding divisions may be winding divisions on a low-voltage side.
The first and second winding divisions may be provided with an identical number of turns.
The stator may be provided with a stator core in which slots are formed at a ratio of two per phase per pole, the slots forming six slot groups each constituted by the slots at intervals of six slots,
the winding phase portions are constructed by connecting in series winding sub-portions installed in adjacent pairs of the slot groups, and
the three-phase alternating-current winding is constructed by forming the winding phase portions into a Y connection.
The stator may be provided with a stator core in which slots are formed at a ratio of two per phase per pole, the slots forming six slot groups each constituted by the slots at intervals of six slots,
the winding phase portions are constituted by winding sub-portions installed in each of the six slot groups,
two equivalent three-phase alternating-current windings each is constructed by forming three of the winding phase portions into a Y connection, and
the winding divisions constituting the winding phase portions constituting identical phases of the two three-phase alternating-current windings are connected in parallel.